Vauxhall M32 6-speed manual transmission.

Background Information

Bearing failure on the M32 gearbox is common more so on vehicles which have been tuned, however standard vehicles also suffer.

Typically you will notice a whining noise when cruising on the motorway in 6th gear. The whining will come and go as you press and release the accelerator. When the bearings wear even more, the gearstick will begin to move as you press/release the clutch in first gear. Minor movements may be due to other things so don’t panic at any movement. The movement is a few cm and very noticeable.

Eventually you may start to see movement in 5th and 6th gear as well, if you see this occurring your gear box really is on borrowed time.

 

Vehicles Affected

Vauxhall have used the M32 gearbox across a wide range of cars, the table below gives an indication of where they were used. It should be noted that to combat the failures, the latest M32 gearbox has been modified in an attempt to get greater oil flow around the enlarged 6th gear bearing.

Astra HAstra JCorsa DInsigniaMerivaMokkaVectra C / SignumZafira B
Z20LEHA14NEL A14NETZ16LER A16LER A16LES Z16LELA14NETZ16LETA17DTSZ22YHZ20LEH
Z20LEL Z20LERA16LETZ13DTHA18XERA14NEL A14NETZ19DT Z19DTHZ20LER
Z16LETA17DTR Z17DTSZ17DTR A17DTSZ16LET A16LETZ22YH
Z19DT Z19DTJ Z19DTHZ19DT Z19DTH
Z13DTH
Z17DTL Z17DTH

Failure Mode

Bearing fatigue and failure is the most common cause of catastrophic failure of the M32 gear box.

The most common bearing to fail first is the one which sits above 6th gear. The photos which follow were from my own failed gearbox which show this 6th gear bearing failure.

 Failed bearing is at the top of the photo

Failed bearing is at the top of the photo

 Excessive play and loose rollers

Excessive play and loose rollers

 Bearing becomes pitted due to metal fatigue

Bearing becomes pitted due to metal fatigue

Providing action is taken before any of the bearings entirely fail the gearbox can be repaired by replacing the bearings throughout. This works out much cheaper than replacing the whole unit. It is possible to split the casing and remove the gears without removing the box from the car, saving the amount of work necessary.




Gearbox Technical Information

The M32-6 is a 6-speed manual transmission. This transmission is being used for the first time in the Astra-H in conjunction with the Z 20 LEL DOHC II turbocharged petrol engine. This manual transmission is an all-synchromesh 3-shaft transmission.
This 3-shaft transmission has the following advantages:

  • Compact construction
  • Improved smooth-running performance
  • Better shift quality
  • High torque transmission
  • Low weight

Structure of the manual transmission

Location of the shafts
The following cross-sectional diagram shows the location of the respective shafts in the M32-6 transmission, as per the 3-shaft principle.
1 Upper main shaft 3 Lower main shaft
2 Input shaft 4 Differential gear

In this transmission angular cone bearings are used for all shafts. These bearings require a certain amount of play and pretension. The required amount of bearing play and pretension is achieved at the production stage by using shims under the angular cone bearing in the transmission housing.

Location of gearwheels

This diagram shows the location of the gearwheels on the respective shaft.

Lower main shaft Input shaft with 1st/2nd gear Upper main shaft
1 1st gear gearwheel 5 3rd/5th gear gearwheel 8 4th gear gearwheel
2 2nd gear gearwheel 6 6th gear gearwheel 9 Reverse gear gearwheel
3 5th gear gearwheel 7 4th gear gearwheel 10 3rd gear gearwheel
4 6th gear gearwheel

One particular advantage of this 3-shaft transmission is that on the input shaft, the 3rd gear gearwheel is also used for 5th gear.

Power flow in the individual gears

The following diagrams show the flow of power in the individual gears.

 

 1st Gear

1st Gear

 2nd Gear

2nd Gear

 3rd Gear

3rd Gear

 4th Gear

4th Gear

 5th Gear

5th Gear

 6th Gear

6th Gear

 Reverse Gear

Reverse Gear







Location of components in the M32-6 transmission

The following exploded diagram shows the location of the components in the M32-6 manual transmission. The components of the individual shafts will then be described.

1 Axle shaft seal ring 6 Axle shaft seal ring
2 Guide sleeve - differential housing 7 Shim
3 Differential housing 8 Differential assembly
4 Seal ring - axle shaft seal ring sealing flange 9 Transmission housing
5 Axle shaft seal ring sealing flange
10 Upper main shaft assembly 16 Central release
11 Input shaft assembly 17 Pressure line
12 Lower main shaft assembly 18 Clutch housing
13 Clutch bleed connector 19 Gearshift assembly
14 Fastening sleeve 20 Magnet
15 Reversing light switch 21 Oil baffle plate

Location of components in upper main shaft assembly

1 Fluid collector pipe 16 Synchro ring
2 Upper main shaft 17 3rd/4th gear shift sleeve
3 Roller bearing - upper main shaft 18 Thrust piece
4 Retaining ring 19 Synchroniser body
5 Needle roller bearing - reverse gear 20 Retaining ring
6 Reverse gear gearwheel (driven) 21 Shim
7 Reverse gear shift sleeve 22 Roller bearing - main shaft
8 Synchro ring - reverse gear 23 Needle roller bearing - 4th gear gearwheel
9 Thrust piece 24 4th gear gearwheel
10 Synchroniser body 25 Intermediate ring
11 Spacer 26 Synchro ring
12 Retaining ring 27 3rd/4th gear shift fork
13 3rd gear gearwheel (driven) 28 Gear shift shaft
14 Needle roller bearing - 3rd gear gearwheel 29 Reverse gear shift fork
15 Intermediate ring

Location of components – lower main shaft assembly

1 Thrust piece 19 6th gear gearwheel (driven)
2 Retaining ring 20 Needle roller bearing - 6th gear
3 1st/2nd gear shift sleeve 21 Roller bearing - main shaft
4 Outer synchro ring 22 Shim
5 Intermediate ring 23 5th/6th gear shift fork
6 Inner synchro ring 24 Gear shift shaft
7 2nd gear gearwheel (driven) 25 1st/2nd gear shift fork
8 Needle roller bearing - 2nd gear gearwheel 26 Synchroniser body
9 Locking ring 27 Outer synchro ring
10 Pressure piece 28 Intermediate ring
11 5th gear gearwheel (driven) 29 Inner synchro ring
12 Needle roller bearing - 2nd gear gearwheel 30 1st gear gearwheel (driven)
13 Synchro ring 31 Needle roller bearing - 1st gear gearwheel
14 Thrust piece 32 Retaining ring
15 Synchroniser body 33 Roller bearing - main shaft
16 Retaining ring 34 Main shaft
17 5th/6th gear shift sleeve 35 Fluid collector pipe
18 Synchro ring

Location of components – input shaft assembly

1 Input shaft seal ring 7 Shim
2 Roller bearing 8 Input shaft bearing
3 Input shaft 9 6th gear gearwheel (driving)
4 1st gear gearwheel (driving) 10 4th gear gearwheel (driving)
5 2nd gear gearwheel (driving) 11 Spacer
6 Input shaft bolt 12 3rd/5th gear gearwheel (driving)

Synchronisation

An improved synchronisation system, already fitted to the F40 manual transmission, is used on the M32-6 transmission. The previous sliding blocks and synchro springs have been dispensed with and have been replaced with thrust pieces.

Matched synchronisation systems are also used for the individual gears.

Two and three-cone synchronisation systems are used.

The synchronisation systems used for each respective gear will be shown in the following.

1st/2nd gearThe three-cone synchronisation system is used for these two gears.
1. Inner synchro ring
2. Intermediate ring
3. Outer synchro ring
4. Shift sleeve
5. Synchroniser body
6. Thrust pieces

3rd/4th gear

A two-cone synchronisation system is used for these two gears.

1. Intermediate ring
2. Synchro ring
3. Shift sleeve
4. Synchroniser body

5th/6th gear

A single-cone synchronisation system is used for these two gears.

1. Synchro ring
2. Shift sleeve
3. Synchroniser body

Reverse gear

Like 5th/6th gear, reverse gear also features a single-cone synchronisation system.

Gearshifting

The M32-6 manual transmission also has a cable gearshift. The individual gears are selected by means of a central gearshift unit.

Mark for the M32-6 manual transmission

The mark for the M32-6 manual transmission consists of a bar code and a combination of numbers.

The letters and numbers located below the bar code have the following meanings:

1 M32 Transmission type
2 O "Opel" design
3 FAM2 Engine family
4 3.941 Ratio
5 C Wheel set
6 XXXXXXXX Serial number
7 NR Transmission code

Transmission fluid

The M32-6 manual transmission uses the same transmission fluid as the F13 / F17 / F17+ / F23 / F25 / F35 and F40 transmissions.

The transmission’s fluid fill quantity is 2.4 litres.

Container size Catalogue number Part number
1 litre SAE 80 19 40 768 9 120 541
60 litres SAE 80 19 40 710 9 194 349

Technical data

The maximum input torque for the M32-6 manual transmission is <strong>320 Nm.</strong>

The weight of the M32-6 manual transmission is approx. 41.5 kg without fluid.

The overall length of the transmission is 329.5 mm.

Transmission ratio

Engine Z 20 LEL
1st gear 3.818
2nd gear 2.053
3rd gear 1.302
4th gear 0.935
5th gear 0.744
6th gear 0.614
Reverse gear 3.727
Output ratio 3.94